The present invention relates to devices for the potentiometric analysis of liquid media and, more particularly, to glass electrodes designed for measuring the oxidation potentials of liquid media over a wide range.
The proposed electrodes will find suitable application in the sensing elements of the systems for the continuous control and monitoring of technological processes in the chemical, pulp- and paper-making, textile, pharmaceutical and microbiological industries as well as in hydrometallurgy.
Electrodes are known in the art for measuring the oxidative potentials in liquid media, comprising sensing elements made of noble metals, such as platinum and gold. These electrodes have the following disadvantages:
Sensing elements made of noble metals are susceptible of a comparatively easy contamination by catalyst poisons (for instance, by SO.sub.2 and other sulphurous compounds); PA1 The presence of gaseous oxygen or hydrogen in a medium being analyzed affects the electrode potential; PA1 Noble metals are capable of catalyzing the decomposition of some redox systems (for instance, of hydrogen peroxide). PA1 SiO.sub.2 -- 32 to 45 PA1 Me.sub.2 O-- 7.0 to 26.0, wherein Me is Li, Na, K PA1 TiO.sub.2 -- 16.0 to 40 PA1 Ti.sub.2 O.sub.3 --0.8 to 4.2 PA1 Nb.sub.2 O.sub.5 and/or Ta.sub.2 O.sub.5 -- 2.0 to 32.0 PA1 SiO.sub.2 -- 32 to 37.4 PA1 Li.sub.2 O-- 0 to 1.8 PA1 Na.sub.2 O-- 5.0 to 8.3 PA1 K.sub.2 o-- 2.2 to 10.7 PA1 TiO.sub.2 -- 26 to 40 PA1 Ti.sub.2 O.sub.3 --0.8 to 1.7 PA1 Nb.sub.2 O.sub.5 -- 4.0 to 25.0 PA1 SiO.sub.2 -- 37.1 to 45 PA1 Na.sub.2 O-- 5.0 to 8.0 PA1 K.sub.2 o-- 6.3 to 17.4 PA1 Li.sub.2 O-- 1.8 to 3.1 PA1 TiO.sub.2 -- 16 to 31.8 PA1 Ti.sub.2 O.sub.3 --1.7 to 4.2 PA1 Nb.sub.2 O.sub.5 -- 10.7 to 21.2 PA1 Ta.sub.2 O.sub.5 -- 2 to 21.3
A glass electrode is also known for measuring the oxidative potential of liquid media, comprising a tubular casing made of a high-resistance glass, having one end thereof tightly sealed to a sensing element being rigidly connected to a current lead disposed within the tube.
The sensing element is made of a glass featuring electronic conduction and consisting of 45 to 65 wt.% SiO.sub.2, 25-50 wt.% Fe.sub.2 O.sub.3, 4 to 15 wt.% Na.sub.2 O, 2 to 10 wt.% Li.sub.2 O.
A significant disadvantage inherent in these electrodes resides in their inability to serve as indicators of the oxidation potentials in strongly acid media having a pH value of below 3, at a temperature of above 60.degree. C.